KR101366772B1 - Motor driving device, and method for cotrolling motor - Google Patents

Abstract

The present invention relates to a motor driving device and a method for controlling a motor. The motor driving device according to one embodiment of the present invention includes: an open-loop driver for performing an open-loop control using a pulse width modulation signal; a closed-loop driver for performing a feedback control using the current revolution per minute of the motor; and a driving controller for controlling one among the open-loop driver and the closed-loop driver to operate by calculating a duty ratio of the pulse width modulation signal and comparing the calculated duty ratio with a preset reference duty. [Reference numerals] (100) Signal generating unit; (20) Motor; (200) Driving controller; (300) Closed-loop driving unit; (400) Open-loop driving unit; (AA) PMM signal

Description

MOTOR DRIVING DEVICE, AND METHOD FOR COTROLLING MOTOR}

The present invention relates to a motor drive device and a motor control method that can reduce the rotational error of the motor at low speed by using a combination of open loop control and closed loop control.

In general, in the case of a motor capable of controlling the speed, such as a BLDC motor, the speed may be controlled by adjusting a duty value of a pulse-width-modulation (PWM) signal. The duty value of the pulse-width-modulated signal is determined between the turn-on time at which the signal has a high value and the turn-off time at which the signal has a low value within one period of the signal. The rotational speed of the motor may be proportional to the duty value of the pulse-width-modulated signal.

The speed control method of the motor can be largely divided into open loop control and closed loop control. In the case of the open loop control, since the feedback circuit is not included, a simple structure can be realized, but the electrical noise is noisy. Errors caused by external factors, etc. cannot be compensated for.

In the case of closed loop control, the speed of the motor is fed back so that a constant speed can be maintained at all times. However, when the speed of the motor decreases due to an external input signal, there is a problem in that the motor is stopped by overshoot. In the case of the closed loop control, the speed control based on a predetermined unit is performed instead of the continuous speed control, and thus there is a limit in that the error degree increases in the low speed region.

Therefore, in the case of using either the open loop control or the closed loop control, there is a limit that is difficult to overcome the above-described problem.

The following prior art documents relate to this prior art and do not disclose a technique using a combination of open loop control and closed loop control.

Japanese Laid-Open Patent Publication No. 1997-247976 discloses a technique for performing open loop control at the initial stage of driving and then closing loop control. However, Japanese Laid-Open Patent Publication No. 1997-247976 has a limitation in that the open loop control and the closed loop control cannot be freely converted.

Japanese Laid-Open Patent Publication No. 2010-98922 discloses a technique for compensating output of a hall sensor with temperature. However, Japanese Laid-Open Patent Publication No. 2010-98922 does not disclose the operation of a mixture of open loop control and closed loop control.

Japanese Unexamined Patent Publication No. 1997-247976 Japanese Unexamined Patent Publication No. 2010-98922

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems of the prior art, and provides a motor driving apparatus and a motor control method which can reduce the rotational error of the motor even at a low speed by using a combination of the open loop control and the closed loop control. .

A first technical aspect of the present invention proposes a motor control device. The motor control apparatus calculates a duty ratio for an open loop driver for performing open loop control using a pulse width modulation signal, a closed loop driver for performing feedback control using a current speed of a motor, and the pulse width modulation signal. And a driving controller configured to control one of the open loop driver and the closed loop driver by comparing the calculated duty ratio with a preset reference duty.

The driving controller may be configured to calculate a duty ratio using the frequency of the pulse width modulated signal received from the pulse width modulated signal, and determine one of a plurality of preset candidate reference duty as the reference duty. The reference duty determiner may include a controller configured to compare the duty ratio and the reference duty to drive the closed loop driver when the duty ratio is greater than the reference duty.

The duty ratio calculator may receive the pulse width modulation signal for a predetermined period and determine the duty ratio by using the number of counter clocks corresponding to the high level among the pulse width modulation signals.

The reference duty determiner includes a plurality of memories respectively storing the plurality of candidate reference duty and a plurality of switches connected to each of the plurality of memories, and any one connected to the corresponding switches by turning on any one of the plurality of switches. The duty stored in the memory may be determined as the reference duty.

The reference duty determiner may turn on any one of the plurality of switches according to a signal provided from the outside.

The controller may compare the duty ratio with the reference duty to provide a reference speed to the closed loop driver when the duty ratio is greater than the reference duty.

The closed loop driver may detect the current speed of the motor and control the rotation of the motor to reduce an error between the reference speed and the current speed.

The controller may control to drive the open loop driver when the duty ratio is less than the reference duty.

The open loop driver may include a triangular wave generator for generating a triangular wave signal, an open loop synthesizer for synthesizing a control signal and the triangular wave signal to generate a pulse width modulated signal, and the pulse width modulated signal generated by the open loop synthesizer. And an open loop controller to control the drive.

A second technical aspect of the present invention proposes a motor control method. The motor control method includes any one of: (a) calculating a duty ratio for a pulse width modulated signal; and (b) comparing the calculated duty ratio with a preset reference duty. Controlling the motor using the.

The step (a) may include receiving a pulse width modulation signal for a predetermined period and counting the number of counter clocks corresponding to a high level among the received pulse width modulation signals to determine a duty ratio.

In the step (b), (b-1) comparing the duty ratio and the reference duty; (b-2) if the duty ratio is greater than the reference duty, controlling the motor using the closed loop drive control. And (b-3) if the duty ratio is less than the reference duty, controlling the motor using the open loop drive control.

The step (b-2) may include detecting a current speed of the motor, comparing the current speed with a reference speed, and controlling rotation of the motor such that an error between the reference speed and the current speed is reduced. It may include.

The step (b-3) may include generating a pulse width modulated signal by synthesizing the control signal and the triangular wave signal, and controlling driving of the motor according to the pulse width modulated signal.

According to one embodiment of the present invention, the combination of the open loop control and the closed loop control can reduce the rotational error of the motor even at low speed.

1 is a graph showing the relationship between PWM duty and RPM in motor control.
2 is a graph showing a relationship between a triangle wave and PWM speed control.
3 is a block diagram for explaining a motor control apparatus according to an embodiment of the present invention.
4 is a detailed configuration diagram for describing an embodiment of the drive control unit of FIG. 3.
FIG. 5 is a detailed circuit diagram for describing an embodiment of the drive controller of FIG. 4.
FIG. 6 is a detailed configuration diagram illustrating an embodiment of the closed loop drive unit of FIG. 3.
FIG. 7 is a detailed configuration diagram for describing an embodiment of the open loop driver of FIG. 3.
8 is a flowchart illustrating a motor control method according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

The identification codes (for example, a, b, c, etc.) for each step, which will be used below, are used for convenience of explanation, and thus the identification code does not describe the order of each step. Thus, each step may occur differently than the order specified unless the context clearly states a particular order. That is, each step may occur in the same order as described, may be performed substantially concurrently, or may be performed in reverse order.

In the drawings referred to in the present invention, elements having substantially the same configuration and function will be denoted by the same reference numerals, and the shapes and sizes of the elements and the like in the drawings may be exaggerated for clarity.

1 is a graph showing the relationship between PWM duty and RPM in motor control.

As shown in FIG. 1, the pulse width modulation (PWM) duty and the revolution per minute (RPM) of the motor may have a proportional relationship. In other words, as the PWM duty increases, so does the RPM.

According to an embodiment, if the minimum speed and the maximum speed are each set to a specific speed, as shown in FIG. 1, the PWM duty and the RPM may have a linear relationship between the minimum speed and the maximum speed.

2 is a graph showing a relationship between a triangle wave and PWM speed control.

As shown in FIG. 2, the duty of the pulse width modulated signal may be determined using a predetermined reference signal (eg, triangular wave) and a control signal. Therefore, when the regulation signal is a low voltage, the PWM duty is increased, thereby increasing the speed of the motor. On the other hand, when the regulating signal is at a high voltage, the PWM duty is lowered, thereby reducing the speed of the motor.

Open loop control can control the driving speed of the motor using the triangle wave and the control signal. However, such open loop control may have an unstable characteristic, in which an error occurs when an environmental change occurs due to voltage or noise.

Hereinafter, a motor control apparatus and a motor control method according to the present invention will be described with reference to FIGS. 3 to 8.

In the following description, the motor control apparatus and the motor control method according to the present invention can be used by mixing the open loop control and the closed loop control. For example, the present invention may reduce the error of the speed by using the open loop control at low speed, and compensate for the error caused by external factors by using the closed loop control at high speed.

3 is a block diagram for explaining a motor control apparatus according to an embodiment of the present invention.

The motor control apparatus 10 may control the driving of the motor 20 by using any one of the closed loop controller 300 and the open loop controller 400.

In more detail, the motor control apparatus 10 may include a driving controller 200, a closed loop driver 300, and an open loop driver 400. In an embodiment, the motor control apparatus 10 may further include a signal generator 100.

The signal generator 100 may generate a pulse width modulated signal.

According to an exemplary embodiment, the signal generator 100 may be included in at least one of the driving controller 200 or the open loop driver 400, or may be configured as a separate component as shown in FIG. 1.

The driving controller 200 may control to operate either the open loop driver 400 or the closed loop driver 300 using the reference duty.

In one embodiment, the driving controller 200 calculates a duty ratio for the pulse width modulated signal, and compares the calculated duty ratio with a preset reference duty to determine which of the open loop driver 400 or the closed loop driver 300. You can control one to work.

The driving control unit 200 will be described later in more detail with reference to FIGS. 4 to 5.

The closed loop driver 300 may perform feedback control using an error between the current speed of the motor and the pulse width modulated signal, and the open loop driver 400 may perform the open loop control using the pulse width modulated signal. Can be.

The closed loop driver 300 and the open loop driver 400 may be implemented in various forms. That is, in the present invention, the specific configurations of the closed loop driver 300 and the open loop driver 400 are not limited to specific embodiments. Accordingly, the embodiments of the closed-loop driver 300 and the open-loop driver 400 to be described below with reference to FIGS. 6 and 7 are only one of various embodiments, and should not necessarily be described with reference to FIGS. 6 and 7. It is clear that it is not limited to the disclosed configuration.

4 is a detailed configuration diagram for describing an embodiment of the drive control unit of FIG. 3, and FIG. 5 is a detailed circuit diagram for describing an embodiment of the drive control unit of FIG. 4.

Hereinafter, various embodiments of the driving controller 200 will be described with reference to FIGS. 4 and 5.

The driving controller 200 may include a duty ratio calculator 210, a reference duty determiner 220, and a controller 230. In one embodiment, the drive controller 200 may further include a switch 240.

The duty ratio calculator 210 may calculate the duty ratio of the pulse width modulated signal. For example, the duty ratio calculator 210 may receive a pulse width modulated signal and calculate a duty ratio using a frequency of the received pulse width modulated signal.

According to an embodiment, the duty ratio calculator 210 may receive a pulse width modulated signal for a predetermined period and determine the duty ratio by using the number of counter clocks corresponding to a high level among the received pulse width modulated signals. have.

For example, the duty ratio calculator 210 may receive a pulse width modulation signal for a predetermined period, where the predetermined period may be counted through a counter. Assuming that the pulse width modulated signal is 1 kHz and the counter clock is 1 MHz, the counter counts 1,000 times during one period of the pulse width modulated signal. The duty ratio calculator 210 may determine the pulse width modulation duty ratio by calculating only an output that is indicated as High among 1,000 counter clocks. For example, if 500 outputs appear as high, the duty ratio calculator 210 may calculate 50% as the duty ratio.

According to an embodiment, the duty ratio calculator 210 may use a plurality of periods of the pulse width modulated signal. In the example described above, when 100 cycles of the pulse width modulation signal are used, 100,000 counting clocks may occur, and the pulse width modulation duty ratio may be determined by calculating an output that is indicated as High among these 100,000 counting results. In this embodiment, since the accumulated period is used, a more accurate duty ratio can be calculated.

The reference duty determiner 220 may determine the reference duty. Here, the reference duty is compared with the duty ratio calculated in the duty ratio calculator 210 and used to determine whether to perform open loop control or closed loop control.

In an embodiment, the reference duty determiner 220 may determine any one of the preset plurality of candidate reference duties as the reference duty.

The reference duty determiner 220 may select any one of the plurality of candidate reference duty to determine the reference duty.

Referring to the example illustrated in FIG. 5, the reference duty determiner 220 may include a plurality of memories 221-1 to 221-n and a plurality of switches 222-1 to 222-n. The plurality of memories 221-1 to 221-n may store a plurality of candidate reference duties, respectively. The switches 222-1 to 222-n may be connected 1: 1 with each of the plurality of memories. The reference duty determiner 220 may turn on any one of the plurality of switches 222-1 to 222-n to determine the duty stored in any one memory connected to the switch as the reference duty.

In an embodiment, the reference duty determiner 220 may turn on any one of the plurality of switches according to a signal provided from the outside.

According to this embodiment, since the speed at which the open loop control can be performed can be variably operated, the present invention can provide various controls for driving of the motor.

The controller 230 may compare the duty ratio with the reference duty to control to operate either the closed loop driver 300 or the open loop driver 400. In the example in which 25% is determined as the reference duty, if the current duty ratio is 25% or less, the controller 230 may control to open-loop control, and if it exceeds 25%, to control closed-loop control. have.

In one embodiment, the controller 230 may control to reduce the error using open loop control if it is below a certain speed. That is, the constant speed may be determined as the reference duty, and the controller 230 may control the open loop driver 400 to operate when the duty ratio is less than the reference duty. Therefore, the controller 230 may control to drive the closed loop driver 300 when the duty ratio is greater than the reference duty.

In one embodiment, the controller 230 may provide a reference speed to the closed loop driver 300 if the duty ratio is greater than the reference duty. Here, the reference speed may be a preset value or a value set by a control command provided from the outside.

FIG. 6 is a detailed configuration diagram illustrating an embodiment of the closed loop drive unit of FIG. 3.

The closed loop driver 300 may control the current speed to change to match the reference speed by comparing the reference speed with the current speed of the motor.

In more detail, the speed detector 320 may detect the current speed of the motor by detecting a change in the level of the hall signal provided from the hall sensor 30.

The closed loop comparator 330 outputs a result of comparing the current speed with the reference speed, and the closed loop controller 310 increases or decreases the speed of the motor 20 based on a value provided from the closed loop comparator 330. Can be controlled.

In one embodiment, the closed loop comparator 330 may detect the current speed of the motor 20 and control the rotation of the motor 20 to reduce the error between the reference speed and the current speed.

As such, closed-loop control enables feedback on the current speed of the motor 20, so that a relatively consistent speed control is possible.

Here, the reference speed may correspond to the desired pulse width modulation duty ratio, and the speed control may be controlled in a step determined by the digital register. For example, assuming that the maximum RPM of the motor is 10000, if the unit is 1%, the RPM will increase to at least 100 units. If the 5950 RPM is to be controlled, the output of 5900 or 6000 will cause an error of a maximum of 50 RPM.

The magnitude of this error may be small at high speeds, but at low speeds (eg 500 RPM), an error of 50 RPM will be about 10%, resulting in significant differences. Therefore, the present invention can drive the motor to reduce the error at low speed by performing the open loop control rather than the closed loop control at low speed.

In the example shown in FIG. 6, an example in which the hall sensor 30 is used to detect the speed of the motor 20 is illustrated, but the closed loop driver 300 of the present invention is not necessarily limited to this example. Do. That is, even when velocity is measured by a Back Electro Motive Force (EMF) signal, closed loop control can be performed as described above.

FIG. 7 is a detailed configuration diagram for describing an embodiment of the open loop driver of FIG. 3.

The open loop controller 400 may include a triangular wave generator 410, an open loop synthesizer 420, and an open loop controller 430.

The triangular wave generator 410 may generate a triangular wave signal.

The open loop synthesizer 420 may generate a pulse width modulated signal by combining the control signal and the triangular wave signal.

The open loop controller 430 may control the driving of the motor 20 according to the pulse width modulated signal generated by the open loop synthesizer 420.

8 is a flowchart illustrating a motor control method according to an embodiment of the present invention.

Referring to FIG. 8, the motor control apparatus 10 may calculate a duty ratio with respect to the pulse width modulated signal (S810).

The motor control apparatus 10 may determine the reference duty (S820), compare the calculated duty ratio with the reference duty (S830), and control the motor using any one of an open loop drive control and a closed loop drive control. There are (S840 through S860).

In one embodiment of step S810, the motor control apparatus 10 receives the pulse width modulation signal for a predetermined period, and determines the duty ratio by counting the number of the counter clock corresponding to the high level of the input pulse width modulation signal Can be.

The motor control apparatus 10 may compare the duty ratio with the reference duty, and if the duty ratio is greater than the reference duty (S840), the motor control apparatus 10 may control the motor by using the closed loop driving control (S850). On the other hand, if the duty ratio is less than the reference duty (S840, NO), the motor can be controlled using the open loop drive control (S860).

In one embodiment for the step S850 (closed loop control), the motor control device 10 may detect the current speed of the motor 10 and compare the current speed with the reference speed. The motor control apparatus 10 may control the rotation of the motor 10 to reduce the error between the reference speed and the current speed.

In one embodiment (open loop control) for step S860, the motor control apparatus 10 generates a pulse width modulated signal by combining the adjustment signal and the triangular wave signal, and drives the motor 10 in accordance with the pulse width modulated signal. Can be controlled.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the particular forms disclosed. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

10: Motor control device
100: signal generator
200: drive control unit
210: Duty Ratio Calculator
220: reference duty determiner
230:
240: Switch
300: closed loop drive unit
310: closed loop controller
320: speed detector
330 closed loop comparator
400: open loop drive
410: triangle wave generator
420: open loop synthesizer
430: open loop controller
20: Motor
30: Hall sensor

Claims (14)

In the motor control device,
An open loop driver configured to perform open loop control using a pulse width modulated signal;
A closed loop driver configured to perform feedback control by using an error between the current speed of the motor and the pulse width modulated signal; And
And a driving controller configured to calculate a duty ratio with respect to the pulse width modulated signal, and to control the one of the open loop driver and the closed loop driver by comparing the calculated duty ratio with a preset reference duty.
The drive control unit
A duty ratio calculator configured to receive the pulse width modulated signal and calculate a duty ratio using a frequency of the received pulse width modulated signal;
A reference duty determiner configured to determine one of a plurality of preset candidate reference duties as the reference duty; And
And a controller configured to compare the duty ratio with the reference duty so as to drive the closed loop driver when the duty ratio is greater than the reference duty.
delete The method of claim 1, wherein the duty ratio calculator
And a pulse width modulation signal is input for a predetermined period, and the duty ratio is determined using a number of counter clocks corresponding to a high level among the input pulse width modulation signals.
The method of claim 1, wherein the reference duty determiner
A plurality of memories respectively storing the plurality of candidate reference duties; And
A plurality of switches connected to each of the plurality of memories;
And turning on any one of the plurality of switches to determine the duty stored in any one memory connected to the switch as the reference duty.
The method of claim 4, wherein the reference duty determiner
A motor control device for turning on any one of the plurality of switches in accordance with a signal provided from the outside.
2. The apparatus of claim 1, wherein the controller
And comparing the duty ratio with the reference duty to provide a reference speed to the closed loop driver when the duty ratio is greater than the reference duty.
The method of claim 6, wherein the closed loop drive unit
Detecting a current speed of the motor and controlling rotation of the motor to reduce an error between the reference speed and the current speed.
2. The apparatus of claim 1, wherein the controller
And control the motor to drive the open loop driver when the duty ratio is less than the reference duty.
The method of claim 8, wherein the open loop drive unit
A triangular wave generator for generating a triangular wave signal;
An open loop synthesizer for synthesizing a control signal and the triangle wave signal to generate a pulse width modulated signal; And
And an open loop controller for controlling driving of the motor according to the pulse width modulation signal generated by the open loop synthesizer.
(a) calculating a duty ratio for the pulse width modulated signal; And
(b) comparing the calculated duty ratio with a preset reference duty to control the motor using any one of an open loop drive control and a closed loop drive control;
The step (b)
(b-1) comparing the duty ratio with the reference duty;
(b-2) if the duty ratio is greater than the reference duty, controlling the motor using the closed loop drive control; And
(b-3) if the duty ratio is less than the reference duty, controlling the motor using the open loop drive control.
11. The method of claim 10, wherein step (a)
And receiving a pulse width modulated signal for a predetermined period and counting the number of counter clocks corresponding to a high level among the received pulse width modulated signals to determine a duty ratio.
delete The method of claim 10, wherein step (b-2)
Detecting a current speed of the motor;
Comparing the current speed with a reference speed; And
And controlling the rotation of the motor to reduce an error between the reference speed and the current speed.
The method of claim 10, wherein step (b-3)
Synthesizing the control signal and the triangular wave signal to generate a pulse width modulated signal; And
And controlling driving of the motor according to the pulse width modulation signal.

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